The present invention relates to novel cyclic peptide compounds which are antagonists of neurokinin A and pharmaceutically acceptable salts thereof. It is an object of the present invention, therefore, to provide new and useful compounds and pharmaceutically acceptable salts thereof.
Neurokinin A and related tachykinins, substance P and neurokinin B, are a group of naturally occurring peptides shown to have a wide distribution within body tissue and produce a myriad of biological effects. Although there is evidence for a role for tachykinins in the central nervous system, the majority of their effects have been studied in peripheral tissues. For example, neurokinin A potently contracts airway smooth muscle while producing minor effects on mucus secretion, vasodilatation and microvascular leakage suggesting a primary utility of these compounds as novel anti-bronchoconstrictor agents. Other tissues in which neurokinin A has been shown to produce smooth muscle contraction includes iris sphincter, various parts of the gastrointestinal tract, vasculature, genitourinary system including ureter, renal pelvis and urinary bladder suggesting a use for tachykinin antagonists as antispastic agents.
A further object of the present invention is to provide compounds, or pharmaceutically acceptable salts thereof, for the treatment and prevention of various diseases in a patient in need thereof. Since it is also believed that tachykinins are involved in inflammation and immune functions, they are potentially useful in the treatment of conditions associated with inflammation, including asthma, allergies, bronchitis, rhinitis, Crohn's disease, ulcerative colitis, rheumatoid arthritis, osteoarthritis, migraine, cystitis and hypersensitivity reactions. Tachykinin antagonism may also be appropriate therapy for the treatment of cough, pain, peripheral neuropathy, post-herpetic neuralgia, adverse immunological reactions, emesis, blood flow disorders due to vasodilatation, ophthalmic diseases, such as conjunctivitis and cutaneous diseases such as contact dermatitis, atopic dermatitis, urticaria and the like. Various central nervous system disorders including anxiety, depression, psychosis, schizophrenia and dementia may also be amenable to treatment with tachykinin antagonists.